Barcelona are sweating over the fitness of defenders Jordi Alba and Gerard Pique after the duo limped off in the Champions League win over Manchester City.
Alba only recently returned to fitness from a hamstring injury and limped off after 10 minutes to be replaced by Lucas Digne during the 4-0 win over City at Camp Nou on 19 October.
Pique was replaced by Jeremy Mathieu later on in the first half after clashing with David Silva.
Barcelona confirmed that Alba had aggravated his hamstring problem, while Pique suffered a sprained ankle.
"Both players will have further tests on Thursday to ascertain the exact extent of their injuries," a statement on the club's official website said.
The injuries are a blow to Barcelona ahead of a tough run of fixtures that includes trips to Valencia and Sevilla in La Liga and Manchester City in the Champions League.
Luis Enrique has Samuel Umtiti available for the trip to the Mestalla on 22 October after the French centre-back came through 90 minutes of the City match unscathed.
The 22-year-old was on the sidelines for a month with a knee injury but slotted in seamlessly to the Barca defence on his return to help them keep a clean sheet against the Premier League leaders.
"Umtiti played very well at right centre-back, which he did before with France's U-21 team," Barca boss Luis Enrique was quoted as saying.
Enrique also lauded Lionel Messi's impact after the Argentina captain struck a brilliant hat-trick to power Barca to a comprehensive win.
"He was decisive," the 46-year-old coach stated. "He was involved in all the game's key moments.
"Messi finishes as if he were playing on the school playground. It doesn't matter if he's coming off an injury. It's just the way he processes the game."
Barcelona have won three out of three games in Champions League Group C and hold a five-point lead over second-placed City.